The present invention relates generally to lighting fixtures and, more particularly, to a recessed lighting fixture that provides improved heat dissipation and grounding.
Recessed lighting fixtures are well known in the art. Ideally, such fixtures are designed to be visually unobtrusive in that very little of the lighting fixture is visible from below the ceiling. However, some trim portions are visible as well as the light sources. An opening is cut into the ceiling into which most of the light fixture is mounted so that very little extends below the plane of the ceiling. A trim piece, which may take the form of a bezel, is generally located at the opening to enhance the appearance of the light fixture and conceal the hole cut into the ceiling. Typically, the trim piece is slightly below the planar surface of the ceiling.
Such bezels or other types of trim pieces also include insulation located between the trim piece and the ceiling. In many cases, recessed lighting fixtures are installed in holes in ceilings where the temperature is much different from that of the room into which the light fixture provides illumination. The insulation tends to oppose changes of the room temperature due to the hole cut in the ceiling for the light fixture.
Although described in a ceiling embodiment, such light fixtures are also used in walls in both dwelling structures and in automobiles, in numerous commercial building applications, and in many other applications. For the sake of reference, such lighting fixtures are referred to herein as “recessed.”
Different light sources are used for recessed lighting fixtures. Some light sources generate substantial amounts of heat, so much so that the rating of the light fixture must be displayed and warnings given that light sources above a certain wattage could pose an overheating danger and are not to be used. However, in some cases, the light fixture must be located a substantial distance away from the object to be illuminated and higher wattage light sources are necessary to develop the amount of illumination needed. Such wattage limits imposed by the lighting fixtures can undesirably limit the amount of light furnished by the fixture. For example, light fixtures located in higher ceilings, which are more common today, or light fixtures that are meant to shine at an angle other than perpendicular to illuminate an object, may not provide enough light for the object if lower wattage light sources must be used. Consequently, light fixtures able to accommodate higher heat levels are desired in such situations. Such light fixtures must be able to dissipate increased levels of heat to avoid a hazard.
There are two basic configurations of recessed lighting fixtures. One is know as a fixed position light source and the second is known as a movable or gimbaled light source. The first does not permit the light source to be aimed differently than when it was mounted while the second permits relatively easy movement of the light fixture for changing the aim of the light. In the second configuration, movement of the light source to change its aim without disassembly of the fixture is provided. Both types are useful for many applications and in both, the dissipation of heat is a concern.
Gimbaled lighting fixtures were created in which the light can be easily aimed. As is commonly used, a gimbaled mounting provides two mutually perpendicular and intersecting axes of rotation thus giving free angular movement in two directions. In the case of a recessed light source, a gimbaled mounting would provide for tilting the light source to achieve elevational control of its aim, and swiveling, or rotating, the light source to achieve azimuth control. This aiming procedure would typically be performed by a person who must touch the light source while it is in the “on” configuration; i.e., while power is being applied to the light source, so that the direction of light can be seen during adjustment. Touching the light source for aiming or other purposes while “on” exposes the person to any electrical potential or charge residing at the light source. Even if not aiming the light source, touching it for the purpose of repair or replacement can subject the person to any electrical potential residing on the light source. Dissipating heat and any electrical potential are two needs that have been identified for recessed lighting fixtures.
As a brief overview of a recessed light source fixture, a recessed “can” or housing is fixedly mounted into the ceiling through the opening. Such housings are generally metallic and electrically conductive. They also are generally connected to earth ground. A “trim unit,” which includes one or more light sources, a trim ring, and other devices to provide the aesthetic design and lighting functions is mounted within the housing. Various “trim units” may be available for mounting within any one housing. The trim unit typically receives the light bulb or other light source or sources and provides the necessary electrical power to them for illumination.
Various structures have been devised for holding a trim unit in a can. One desired structure is the use of devices that interlock or mate with other devices to positively hold the trim unit in place in the can. Other approaches involving only friction to maintain the trim unit in place are less desirable. It would also be desirable for such mounting devices to form an electrical pathway to the can so that any electrical charge that may build up on the trim unit can be dissipated.
Hence, those skilled in the art have recognized the need for a light fixture in which brighter light sources can be used and any commensurate higher levels of heat can be dissipated. Those skilled in the art have also recognized a need for providing improved means for dissipation of heat from light sources and electrical supply devices used in recessed light fixtures, and for providing the dissipation of any electrical energy that may be developed at the light fixture, in particular at the part of the fixture more likely to be touched by a person attempting to repair or aim the light source. A need has also been recognized for a positive mounting arrangement of the trim unit in the recessed housing so that the trim unit is held in the housing through an interference or interlocking mounting system sufficient to prevent the trim unit from falling out of the recessed housing. The present invention fulfills these needs and others.